Wireless portable automated harness scanner system and method therefor

ABSTRACT

The present document describes an assembly for interfacing an existing harness connector of an installed wiring harness to a test module, the assembly comprising: a harness-specific connector for connecting to the existing harness connector; a test box connector module connected to the harness-specific connector and for connecting to a test module, the test box connector module comprising a key which is unique to the test box connector module and which is used to identify the test box connector module when connected to the test module. There is described a method for identifying a test box connector module used in testing an installed wiring harness comprising an existing harness connector, the method comprising: connecting the test box connector module to a test module; detecting a key which is unique to the test box connector module thereby determining the identity of the test box connector module; sending the identity of the test box connector module to a user interface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35USC§120 of allowed U.S.non-provisional patent application Ser. No. 10/932,309, filed Sep. 2,2004, bearing the same title, the specification of which is herebyincorporated by reference.

TECHNICAL FIELD

The invention relates to a system and method for testing and repairinginstalled wiring harnesses.

BACKGROUND OF THE INVENTION

An electrical wiring harness typically comprises a bundle of individualconnector wires of varying gauges, impedances and types, all arrangedand distributed at different locations within an installation, such as atransport vehicle. Such wiring harnesses are usually bound together inorder to facilitate the installation, repair and maintenance of thewires. The transport vehicle industry, especially the aviation and theautomobile industries, makes extensive use of such wiring assemblies.

In the aircraft industry, wiring harnesses are used to interconnect thevarious components and subassemblies located within an aircraft. Thenumber of possible electrical interconnections within a harness growsexponentially with the number of wires and connectors. Therefore,electrical problems within a harness are incredibly hard to identify andlocate, especially for already installed harnesses.

In the prior art, a typical method of testing an installed harness is byusing a ringing cable. Unfortunately, such a method is inconvenient asit presents numerous drawbacks. Such a method requires that a pluralityof operators be deployed at various connection points along the wiringharness, their locations being chosen in accordance with electricalschematics, and the operators communicating and coordinating testingprocedures through walkie-talkies. With prior art methods, the operatorshave to ring cables, one at a time, which requires many operators forcomplex or multiple connections.

Another prior art method of testing a wiring harness involves connectingdevices to the installed harness via cables and performing the testing.However, such a method requires installation of interface cables andother components from the system for testing. Additionally, it requiresthe deployment of many operators and the use of maintenance manuals,which makes the process time-consuming, expensive and prone to humanerror.

Another problem in the prior art is that of keeping accurate records ofthe results of testing and maintenance procedures. Currently, suchinformation is manually recorded by operators into wiring diagramsand/or work orders, a practice which is prone to errors and omissionsand which does not allow for analysis of the data recorded over time.

Testing devices such as TDR testing units have been developed to testwiring harnesses, one wire at a time. Unfortunately, prior art TDRmethods do not allow for performing testing on multiple wires at a time,which proves to be time consuming and does not allow for gatheringcomplete and accurate information regarding the wires.

There exists therefore a need for a system and a method for testing aninstalled wiring harness, which is time and cost efficient.

Additionally, there exists a need for a system and method for testing aninstalled wiring harness, which is not prone to human error.

Furthermore, there exists a need for adequate documentation followingtesting procedures.

According to an embodiment, there is provided a method for testing aninstalled wiring harness, comprising: providing a signal source testingmodule at a first connection point in the wiring harness; providing ameasurement termination testing module at a second connection point inthe wiring harness; providing a central management module forcontrolling the testing modules to coordinate the testing modules tosend testing signals from the first connection point to the secondconnection point, after disconnecting electrical power between theconnection points, for performing tests and recording test measurementsof the installed wiring harness; and the signal source testing moduleand measurement termination testing module for sending the testmeasurements to the management module.

According to an embodiment, there is provided a system for offlinetesting of an installed wiring harness, comprising: at least a first anda second testing module, having: a communication module for receivingtest specifications and for sending test measurements; testing equipmentfor generating the test measurements from the test specifications; eachof the first and second testing modules being adapted for connection ata connection point in the wiring harness; a central network managementmodule, having: a communication module for providing the testspecifications to the testing modules and for receiving the testmeasurements; and a test management module for controlling the testingmodules.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide a systemand method for testing an installed wiring harness, which allowsautomated testing of multiple lines simultaneously, thereby reducing thetime and the cost of the testing procedure.

It is another object of the present invention to provide a system andmethod for testing an installed wiring harness, which is automated,thereby eliminating human error.

It is yet another object of the present invention to provide a systemand method for testing an installed wiring harness which allows toproduce automatically standardized maintenance reports and electroniclogbook.

According to an aspect of the invention, there is provided a method fortesting an installed wiring harness, comprising: providing a signalsource testing module at a first connection point in the wiring harness;providing a measurement termination testing module at a secondconnection point in the wiring harness; providing a central managementmodule for controlling the testing modules to coordinate the testingmodules to send testing signals from the first connection point to thesecond connection point, after disconnecting electrical power betweenthe connection points, for performing tests and recording testmeasurements of the installed wiring harness; and the signal sourcetesting module and measurement termination testing module for sendingthe test measurements to the management module.

According to another aspect of the invention, there is provided a systemfor offline testing of an installed wiring harness, comprising: at leasta first and a second testing module, having: a communication module forreceiving test specifications and for sending test measurements; testingequipment for generating the test measurements from the testspecifications; each of the first and second testing modules beingadapted for connection at a connection point in the wiring harness; acentral network management module, having: a communication module forproviding the test specifications to the testing modules and forreceiving the test measurements; and a test management module forcontrolling the testing modules.

According an embodiment, there is provided an assembly for interfacingan existing harness connector of an installed wiring harness to a testmodule, the assembly comprising: a harness-specific connector forconnecting to the existing harness connector; a test box connectormodule connected to the harness-specific connector and for connecting toa test module, the test box connector module comprising a key which isunique to the test box connector module and which is used to identifythe test box connector module when connected to the test module.

According an embodiment, there is provided a method for identifying atest box connector module used in testing an installed wiring harnesscomprising an existing harness connector, the method comprising:connecting the test box connector module to a test module; detecting akey which is unique to the test box connector module thereby determiningthe identity of the test box connector module; sending the identity ofthe test box connector module to a user interface.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the present invention will becomeapparent from the following detailed description, taken in combinationwith the appended drawings, in which:

FIG. 1 is a block diagram of an automated harness scanner systemaccording to a preferred embodiment of the present invention;

FIG. 2 is a block diagram of a test module connected to a wiring harnessaccording to a preferred embodiment of the present invention;

FIG. 3 is a block diagram of an analysis module according to a preferredembodiment of the present invention;

FIG. 4 is a diagram of an automated harness scanner system having acentral management system and distributed test modules according to apreferred embodiment of the present invention.

FIG. 5 is a schematic diagram of two test modules installed in a wiringharness, testing a wire showing a break point.

FIG. 6 is a graph of an exemplary TDR return signal obtained whenapplying a pulse input signal to a wire without shielding defects.

FIG. 7 is a graph of an exemplary TDR return signal obtained whenapplying a pulse input signal to a wire with shielding defects.

It will be noted that throughout the appended drawings, like featuresare identified by like reference numerals.

DETAILED DESCRIPTION

As illustrated in FIG. 4, the present invention is a fully portableautomated test system allowing verification of any type of installedwiring harness 27 using a new open platform architecture for thetransport industry. Even though the testing system shown in FIG. 4 isused for testing a wiring harness installed in a plane, the testingsystem could also be used for testing a wiring harness installed in anyother installation for which periodical testing, diagnosis andmaintenance is required. Such other installations might include, but arenot limited to, boats, ships, trains, cars, etc.

In the preferred embodiment of the present invention, the automatedtesting system is a distributed network, comprising a plurality of testmodules 31 which are connected to the wiring harness 27 at the locationof existing harness connectors 29. The test modules 31 are incommunication with a central Network Management System (NMS) 10, fromwhich the test modules 31 receive information regarding the testing ofthe wiring harness 27 and to which they send back test results followingcompletion of testing.

In one embodiment of the present invention the test modules 31communicate with the NMS 10 over a wireless connection, using a protocolsuch as TDMA in order to support a large number of test modules 31, suchas in the case of testing a wiring harness 27 having a plurality ofconnectors at different locations. It is however within the scope of thepresent invention that the test modules 31 send and receive informationthrough a cable connection.

The NMS 10 is preferably a computer system having input means, displaymeans and storage means and/or other components well-known to thoseskilled in the art. In the preferred embodiment of the presentinvention, the computer system includes, for example, a centralprocessing unit (CPU), random access memory (RAM), read-only memory(ROM), as well as various peripheral devices, each connected to a localbus system. Also coupled to the local bus system are a mass storagedevice, a keyboard, a pointing device (mouse, trackball, touchpad,etc.), a communication device, etc. The communication device is anydevice allowing the computer system 11 to communicate with a remotelylocated device over a communication link, such as a telephone modem,cable modem, ISDN, wireless, etc.

Now, with respect to FIG. 1, the preferred architecture of the NMS 10according to the present invention will be described. The datamanagement module 13 contains all the software required to interfacewith external storage module 14 as well as the NMS data storage 12. Theexternal storage 14 contains an electronic logbook unique to eachtransport vehicle, which contains all transport vehicle electricalinformation, wiring harness signature and past test results. The NMSstorage 12 contains all the historical data, statistical variation dataand modeling information for a particular wiring harness 27. The datamanagement module 13 is a software configuration management toolallowing to control and validate information to be stored in thetransport vehicle electronic logbook and NMS storage 12. Compressiondata algorithms are preferably used for storing and managing data in anefficient manner on the storage units 12, 14.

The data management module 13 receives data from a signature buildermodule 11. The signature builder module 11 generates a wiring harnesssignature for a given transport vehicle harness 27 based onmanufacturing specs. The module 11 generates a listing of the transportvehicle wiring harness basic characteristics and properties in terms ofmaterial, gauge, length, resistance, impedance, tolerance, conductivity,cross-talk, insulation and many more. The wiring harness signature maybe uploaded by transferring raw data from the transport vehiclemanufacturer database. This can be achieved by directly accessing thedatabase or by providing the manufacturing specs on a CD-ROM to thesystem. Alternatively, the wiring harness signature can be generated byconnecting the testing system to the transport vehicle wiring harness27. In the case the wiring harness signature is generated, it is theartificial intelligence module 15 that provides it to the datamanagement module 13.

The artificial intelligence module 15 is a self-learning tool foroptimization which enables modification of its own program based on itslearning experience. The artificial intelligence module 15 providesdiagnosis and recommendations based on historical data, models and testdata results received from the test modules 31 through the communicationmodule 21.

As shown in FIG. 3, in the preferred embodiment of the presentinvention, the artificial intelligence module 15 includes a signatureupdate module 49 and an analysis module 51. The signature update module49 manages historical data, statistical data and signature updates fromtest results received from test modules 31. If a signature is notavailable for a given installed wiring harness 27, the signature module49 allows building a signature by performing a series of test andgathering a set of electrical characteristics of the wiring harness 27.When the signature update module 49 receives the test results from allthe test modules 31 and no signature is available for a specifictransport vehicle wiring harness 27, then it will generate and store theharness signature. The signature update module 49 will propose signaturechanges to the Data Management module 13 by requesting the storage ofall information previously detected and measured such as connectivitytable, Netlist, which describes the connectivity of the wiring harness,or the wire mapping between each connection point, and includes each ofthe wires' physical attributes, and all electrical characteristicsmeasured and provided by test modules 31 in the format of a harnesssignature.

The electrical harness signature contains information that is unique foreach wire of the wiring harness 27. The harness signature for each wiredescribes the electrical characteristics of that particular wire. In thepreferred embodiment of the present invention, the harness signature isa multiple-dimensional array. Table 1 illustrates an exemplary harnesssignature structure:

TABLE 1 VARIABLE TYPE CONNECTION DYNAMIC MULTIPLE DIMENSION ARRAY WIRESPECIFICATION ARRAY DC MEASUREMENTS ARRAY AC MEASUREMENTS ARRAY SWRMEASUREMENTS ARRAY SWR RETURN SIGNALS DYNAMIC MULTIPLE DIMENSION ARRAYTDR RETURN SIGNALS DYNAMIC MULTIPLE DIMENSION ARRAY SPECTRUM IMPEDANCEDYNAMIC MULTIPLE DIMENSION MEASUREMENTS ARRAY

The connection variable is a dynamic, multiple-dimension arraycontaining information in wire connection to other points in the wiringharness 27. The wire specification variable is an array of manufacturerspecifications, such as conductor material, shielding material, gauge,insulation, conductance, dilatation, etc.

The “DC measurements” variable is preferably an array containingmeasured voltage and current values, as well as resistance andconductance values.

The “AC measurements” variable is another array containing voltage andcurrent values measured for different AC input signals. In the preferredembodiment of the present invention, sinusoidal signals of 1 kHz, 100kHz and 1 MHz of 1 V peak-to-peak are used as input signals. The ACmeasurements include values of calculated impedance.

The “SWR measurements” variable is an array containing time delay valuesfor the return signal from an input sinusoidal signal. In the preferredembodiment of the present invention, sinusoidal signals of 1 kHz, 100kHz and 1 MHz of 1 V peak-to-peak are used as input signals. The SWRmeasurements also include values of calculated conductor length or breakpoint based on the Doppler equations.

The “SWR return signals” variable is a dynamic multiple dimension arraycontaining all sample data points for the return signal from an inputsinusoidal signal.

The “TDR return signals” variable is a dynamic multiple dimension arraycontaining all sample data points for the return signal from an inputpulse signal, sent at various frequencies, preferably at 1 KHz, 100 KHzand 1 MHz.

The “Spectrum impedance measurements” variable is another dynamicmultiple dimension array containing measured impedance values, in polarand vector form, for a 1-V peak-to-peak input sinusoidal signal.Preferably, the input sinusoidal is varying over a frequency spectrumfrom 1 KHz to 1 MHz in steps of 50 KHz. This array contains as wellcalculated Nyquist plot data over the 1 KHz to 1 MHz spectrum.

The artificial intelligence module 15 also includes an analysis module,which is a self-learning module with the capability to give a diagnosisand recommendation on a transport vehicle wiring harness 27. Theanalysis module 51 receives test results from the test modules 31. Also,this module 51 receives the harness signature and statistical data fromthe signature update module 49. Then, this module retrieves the wiringharness model from the NMS storage 12 through the data management module13 to perform a diagnosis and recommendation. Thediagnosis/recommendation is sent to the test management module 17.Finally, this module will decide to send or not a new harness modelanalysis to the data management module 13 based on the new learningexperience.

The test management module 17 sends the test specification regarding themeasurements to be performed by each of the test modules of the system.The test management module 17 is also in communication with an analysismodule 15 for receiving either a diagnosis or recommendations and aharness signature for the wiring harness 27. The test management modulecan also provide this information for the operator through a reportmodule 23 or a user interface module 25.

The test management module 17 communicates with the network ofdistributed test modules 31 through a communication module 21. In thepreferred embodiment of the present invention, the communication moduleis a transmitter (emitter/receiver) communicating to each test module 31using a STAR configuration. The module 21 is a HUB assigning andmanaging all frequencies, signal strength, power and time slots in thetesting system.

The report module 23 is an automated tool used to format specialprintouts, such as metallic labels, cable prints, as well as parts andinventory numbers. The report module 23 may also be used as a tool forgenerating Quality Assurance and maintenance reports including the testresults collected during a given test session or past test results. Thereport module 23 receives all the information required from the testmanagement module 17.

The user interface module 25 controls all the man machine interfacesrequired for data input and output. It can display on-line schematicdiagrams, Netlists and any wire characteristics and properties, as wellas the transport vehicle electronic logbook.

The maintenance management module 19 is an assistance tool to anyoperator using the automated testing system. It provides a step-by-stepprocedure to guide the operator in testing a transport vehicle wiringharness 27 for a specific vehicle sub-system. The maintenance managementmodule 19, through the user interface module 25, prompts the operator byasking which sub-system to test and provides the user with informationregarding the number of test modules required, where to connect them andtheir location within the transport vehicle.

In a first step, the operator would identify a faulty subsystem withinthe wiring harness 27, by using on-board computers with built-inself-test (BITES) capabilities. If the subsystem cannot be identified bythe BITES, the operator will review indicators, sensors information aswell as the pilot's flight book to identify the subsystem.

The operator will then load a specific CD-ROM aircraft logbook in thecomputer, which contains all wiring harness information for theparticular aircraft. The system first prompts the operator to enter theaircraft sub-system to test. Then, the HS2000 maintenance programreplies with the number of test modules 31 and test box connectorsmodules required to perform the test as well as the locations ofaircraft connectors to be tested.

The operator then disconnects the aircraft-specific harness connector 29from the aircraft wiring harness 27 and connects the test module 31 withthe appropriate connector module 33. Then, the operator powers on thetest module 31, at which time the test module is automatically assigneda system ID by the NMS. The system ID contains a time slot, frequencyand signal strength according to the TDMA protocol. This procedure isrepeated for all test modules 31 to be connected.

After having installed all test modules 31, the operator then returns tothe computer to start the testing routine. If any problems occurredduring installation, the system will notify the operator. Otherwise, theoperator is prompted to start the test. In this example, the operatorstarts the landing gears controls sub-system test on the computer andreceives the test results indicating any electrical wiring problems,faults and their locations.

The operator will then visually inspect the locations at which theproblems/faults have been identified. Then, the operator will carry onthe repair (splice, solder, connector).

Then the operator returns to the system 10 to retest the sub-systemunder test and the system provides a new set of test results from theelectrical wiring harness. If no other problems are detected, the newharness signature is recorded in the system 10.

As a last step, the operator returns to the aircraft and connects allharness-specific connectors 29 to aircraft harness 27 equipment. Then,the operator re-runs the BITES on the sub-system under test or directlyperforms some trials on the aircraft harness 27 equipment. If problemsare identified on the aircraft harness 27 equipment, then the operatorrestarts the testing procedures.

If no problem occurs, a work order will be issued with the details ofthe repairs, validated by maintenance quality controls, and registeredin the company database. Also, the new electrical harness signature,schematics updates, notes and all other aircraft changes will berecorded in the aircraft electronic logbook, which as in this example,could be a CDROM. Finally, the aircraft electronic logbook is stored inthe aircraft. In the example, the logbook is on CDROM and kept in theaircraft.

A test module 31 is the component that contains all testing equipmentrequired in order to generate the measurements data to support any testspecifications. The Test Specification information received from the NMS10, through the communication module 47, is processed by the measurementmanagement module 45 and sent to the appropriate testing units.

Now referring to FIGS. 1, 2, and 4, test modules 31 connect to aharness-specific connector 29 through a connector module 33. Eachconnector module 33 can be customized for a specific type of harnessconnector 29 or can be of a generic standard connector type. A connectormodule 33 can be connected to more than one harness-specific connector29. The connector module 33 is auto-detected and controlled by themeasurement management control module 45 to identify the number and typeof harness-specific connectors 29 available to be connected to the testmodules 31. Then, the information about the connectors available fortest is sent to the test manager module 17. The harness-specificconnectors 29 connected to the test box connector module 33 are switchedand scanned by the multiplexer module 35.

The multiplexer module is a circuit switch multiplier, which can becascaded as needed to achieve a predetermined number of test points. Itis controlled by the measurement management module 45 and redirects anysignals to the right harness-specific connector 29 wires to be tested.

The measurement management control (MMC) module 45 receives, through thecommunication module 47, test Specification from the NMS 10. The MMCmodule 45 determines which testing units 37, 39, 41, 43 are required toproduce raw data measurements. The module 45 then coordinates andsynchronizes the testing units to avoid any interference. The MMC module45 detects the test box connector module 33 connected to the testmodules 31 using a hardware coded key, which is unique to each test boxconnector module 33. The MMC module 45 sends the list of connectorsavailable to connect the harness specific connector module 29 to the NMS10. Then, the operator will know which connector on the test boxconnector module 33 to plug the harness specific connector 29. Also, theMMC module 45 controls the connector selections and the wires scanningfor each connector. Finally, it produces, stores and sends test resultsinformation to the NMS 10. The test results are produced by equipmentmeasurements, but also by correlating the measurements received from theStanding Wave Ratio (SWR) module 39, Time Domain Reflectometry 41 andspectrum impedance 43 modules. Such combined information is usedspecifically for shielding wire detection, cross-talk and couplingproblems. Signal data processing is used on the return signal from theSWR module 39, TDR module 41 and Spectrum Impedance module 43 to extractand store the information required to characterize the actual conditionof the wire. Then, information from the three modules are correlated andaligned with a transmission line model and wire specification undertest. Finally, the information is sent to NMS 10 to compare with theprevious harness signature and to get a diagnosis.

In the preferred embodiment of the present invention, the initialharness signature is generated from specifications given by theelectrical harness manufacturer or tests performed on the harness.Whenever a test is performed on the wiring harness 27 and a previoussignature exists, the signature comparison is performed as follows.First, a Netlist comparison is performed to verify all connectivitydifferences between the existing signature “connection” variable and thenew measurements. The Al module 15 will perform the comparison. At thesame time, the “DC measurements” and “AC measurements” variables areused to determine whether any “open or “short” problems are presentwithin the harness. If any are detected, the Al module 15 uses the “SWRmeasurements” from the signature to determine the break point locationof “open” or “short” within the length of the wire. As per FIG. 5, thesystem uses a test box unit “TBU” at each end of the wire, giving moreprecision as to the location of the break point within the length of theconductor.

The Al module 15 then uses the “SWR return signals”, “TDR returnsignals” and “Spectrum impedance measurements” in order to detectshielding defects. The information provided by the “TDR return signals”data and the “Spectrum impedance measurements” is used with correlationalgorithms well known in the art to detect a shielding defect. Whenevera shield defect has been identified, the Al module 15 determines itsexact location by using the “SWR return signals” data. Signal processingincluding moving range, correlation and data mining algorithms are usedin order to detect the location of a shielding problem.

FIG. 6 illustrates the “TDR return signal” from a previous harnesssignature, in which no shielding defect is present. FIG. 7 shows the“TDR return signal” received after performing a series of measurementson the same harness after some time. FIG. 7 shows a shielding defectpresent in one of the wires.

In the preferred embodiment of the present invention, the Al module 15uses previously stored “TDR return signal” data to compare the received“TDR return signal” data. If a shielding problem is detected, then theAl module 15 applies correlation and data mining algorithms to thereceived “TDR return signals” data and the received “Spectrum impedancemeasurements” to determine the size of the shielding defect. The Almodule 15 then uses “SWR return signals” data with moving range/Doppleralgorithms to determine the location of the shielding defect. The Almodule 15 can use the other variables data in the received signaturewhenever more data or calculations are required by the Al models todetermine the size or location of shielding defect.

In the case in which the analysis of the received “TDR return signal”data shows a difference when compared to the stored “TDR return signal”data, the significance of the change is assessed in order to determinethe gravity of the problem. At the time of analysis of the data, therelationship between the physical wire characteristics and theelectrical properties of the wire being tested would be taken intoaccount. The relationship between the two would be used to assess theimpact of a change in the physical wire characteristics on theelectrical properties of the wire. Another factor taken into account bythe Al module 15 when performing the assessment is the actual use of thewire being tested. For example, the type of voltage and current carriedby the wire would play a role in determining the sensitivity of theelectrical properties of the wire to changes in its physicalcharacteristics. Such a complete assessment performed by the Al module15 would allow to provide different diagnostics and recommendationsdepending on the gravity of the detected problem. In one case, upondetecting a shielding defect in a wire being tested, the Al module 15might recommend that the wire be replaced, in other cases, the Al module15 might recommend that the wire simply be submitted to a visualinspection, while in other cases, the change would simply be recorded inthe electrical signature without signaling a defect. It is knowledgeabout the use of the wire within the harness system 27 that would allowthe Al module 15 to set different pass/fail thresholds for differenttypes of wire and to make recommendations accordingly.

Now, returning to FIG. 2, the communication module 47 receives testspecifications from the NMS 10 and sends back test results. In thepreferred embodiment of the present invention, the communication module47 is a slave transceiver (Transmitter/Receiver). The module 47 receivesinformation from the NMS 10 and passes it to the MMC module 45.

In the preferred embodiment of the present invention, and as shown inFIG. 2, a test module 31 includes testing units such as: a circuitswitch and polarity analyzer module 37, a standing wave ratio (SWR)module 39, a TDR module 41 and a spectrum impedance module 43.

The main functions of the circuit switch and polarity analyzer module 37are to perform a continuity test and an active electronic componentsverification test. Also, this module 37 performs all DC testing of thetransport vehicle wiring harness 27. The module 37 contains thefollowing two sub-modules: a circuit switch analyzer and a polarityanalyzer.

The circuit analyzer performs a continuity check for all possibleharness connections and produces a mapping connection, which is storedin a table. The polarity analyzer performs a test to verify any activecomponents like transistor, diode or semi-conductors in the wiringharness 27. The polarity analyzer verifies and determines the directionof the current and gathers all the raw data required by the Al module15.

The standing wave ratio module 39 is a testing unit, which sends a puresinusoidal wave through each conductor of the wiring harness 27 andmeasures the return in terms of time, voltage and sinusoidal shape. Itcontains a unique “Transmission Line Model” specific to the transportvehicle industry and a state-of-art data signal processing system inorder to analyze the return signal. The SWR module 39 can calculate thebreak point of a conductor in the wiring harness 27 using Dopplerequations. This module 39 generates raw data measurements required bythe NMS 10 for providing a diagnosis of the wiring harness 27.

The Time Domain Reflectometry (TDR) module 41 is a testing unit, whichsends a small amplitude pulse through each conductor of the wiringharness 27 in order to characterize it. It uses Fast Fourier Transforms(FFT) and Laplace Transforms to compute and produce raw datameasurements and a state-of-art data signal processing system to extractand analyze the return signal.

The spectrum impedance module 43 is a testing unit, which measures ACresistance with different signal voltage over a spectrum of specificfrequencies. The spectrum impedance module 43 produces polar and vectorrepresentations for each wire impedance over a specific frequencyspectrum (Nyquist plot). Also, the spectrum impedance module 43 uses astate-of-art of data signal processing system to extract and analyze thereturn signal for each frequency. The module 43 generates raw datarequired by the NMS 10 and stores the information in a table. In thepreferred embodiment of the present invention, this module 43 hasauto-range calibration abilities using the successive approximationmethod.

The embodiments of the invention described above are intended to beexemplary only. The scope of the invention is therefore intended to belimited solely by the scope of the appended claims.

The invention claimed is:
 1. An assembly for interfacing an existingharness connector of an installed wiring harness to a test module, theassembly comprising: a harness-specific connector for connecting to theexisting harness connector; a test box connector module connected to theharness-specific connector and for connecting to a test module, the testbox connector module comprising a key which is unique to the test boxconnector module and which is used to identify the test box connectormodule when connected to the test module and to identify theharness-specific connector by reference to a user-defined list ordatabase, the harness-specific connector being a separate and distinctentity from the test box connector module, wherein the test boxconnector module is automatically detected by the test module.
 2. Theassembly of claim 1, wherein the key comprises a hardware coded keywhich may be programmable or not.
 3. The assembly of claim 1, whereinthe harness-specific connector comprises more than one harness-specificconnector for connection to the same test box connector module.
 4. Theassembly of claim 3, wherein the key is used to identify each of themore than one harness-specific connector by reference to a user-definedlist or database.
 5. The assembly of claim 4, wherein the key comprisesa hardware coded key.
 6. A method for identifying a test box connectormodule used in testing an installed wiring harness comprising anexisting harness connector, the method comprising: providing the testbox connector module connected to a harness-specific connector which isfor connecting to the existing harness connector, the harness-specificconnector being a separate and distinct entity from the test boxconnector module; connecting the test box connector module to a testmodule; automatically detecting the test box connector module using thetest module; detecting a key which is unique to the test box connectormodule thereby determining the identity of the test box connector moduleand of the harness-specific connector by reference to a user-definedlist or database; sending the identity of the test box connector moduleto a user interface.
 7. The method of claim 6, further comprising, fromthe identity of the test box connector module, identifying theharness-specific connector connected the test box connector module andsending the identity of the harness-specific connector module to theuser interface.
 8. The method of claim 7, wherein the harness-specificconnector comprises more than one harness-specific connector and theidentifying the harness-specific connector comprises, from the identityof the test box connector module, providing a list of the more than oneharness-specific connector to the user interface and the sendingcomprises sending the list of the more than one harness-specificconnector to the user interface.
 9. The method of claim 8, furthercomprising which one of the more than one harness-specific connector isfor connection to an existing harness connector of an installed wiringharness.
 10. The method of claim 9, further comprising testing byswitching and scanning the more than one harness-specific connector. 11.The method of claim 8, further comprising testing by switching andscanning the more than one harness-specific connector.
 12. The method ofclaim 7, further comprising testing by switching and scanning theharness-specific connector.